Trauma is the leading cause of death in children and intra-abdominal injuries (IAI) are a frequent[unreadable] cause of morbidity and mortality due to trauma. Some IAIs are difficult to identify and failure to identify these[unreadable] injuries results in preventable morbidity and mortality. Abdominal computerized tomography (CT) is the[unreadable] reference standard for the diagnosis of IAl. CT scanning, however, has important risks, primarily the risk of[unreadable] development of radiation-induced malignancy. For every 1,500 children undergoing abdominal CT scanning,[unreadable] approximately one child will die from a malignancy induced by the radiation and up to three additional[unreadable] children will develop non-fatal malignancies from this exposure. Only approximately 10% of abdominal CT scans currently performed on children with trauma demonstrate IAIs, thus CT scanning is used inefficiently. Objectives: The[unreadable] objective of this study is to develop highly sensitive, specific and generalizable decision rules for the[unreadable] evaluation of children seen in emergency departments (EDs) with blunt abdominal trauma. These decision[unreadable] rules may then serve to generate evidence-driven guidelines for the evaluation of these children, and when[unreadable] implemented will result in more efficient use of CT scans. Study Design: This will be a prospective,[unreadable] multicenter, observational study of children with blunt abdominal trauma. Setting: Children with blunt[unreadable] abdominal trauma seen at one of 17 hospitals in the Pediatric Emergency Care Applied Research Network[unreadable] (PECARN) will be enrolled over a two year period. The EDs of the PECARN evaluate more than 900,000[unreadable] children of diverse geographic and racial/ethnic background annually. Participants: We will enroll approximately 9,774[unreadable] children with significant blunt torso trauma, including 900 children with IAl. Outcome Measures: The primary[unreadable] outcome for this study will be IAI in need of acute intervention (IAI resulting in death, or an IAI in need of any[unreadable] of the following: laparotomy, blood transfusion, angiographic embolization, or IV hydration).[unreadable] Interventions/Data analysis: The patients' history, physical examination findings and laboratory results at ED[unreadable] evaluation will be analyzed using recursive partitioning to generate a clinical decision rule(s) for the[unreadable] identification of children at high risk and near-zero risk of IAI in need of acute intervention. The decision rule[unreadable] (s) will lead to more efficient use of abdominal CT in those children at risk for IAIs, and a decrease in use in[unreadable] those at near-zero risk of IAI, ultimately resulting in more efficient, safe and effective care of injured children.[unreadable]